COMMON INVESTIGATIONS IN TMJ DYSFUNCTION
Various imaging modalities are available to assess the degree of joint destruction and dysfunction. The main modality used is MRI - Magnetic Resonance Imaging. An inflammatory screening process can be used to help rule out inflammatory conditions such as rheumatoid arthritis.
Often the first imaging modality is an OPG. These can be used as a screening tool for ruling out dental caries and other gross pathology such as cysts and fractures. Occasionally, gross articular changes can be seen in the TMJ(See Figure). However, due to the limited amount of information available regarding the TMJ no soft tissue pathology nor subtle articular surface changes can be elicited. When possible, cone beam CT imaging should be requested which "includes TMJs and occlusion".
Other imaging modalities that are very useful are CT and Bone Scans when indicated.
Magnetic Resonance Imaging
This is used to assess the degree of soft tissue changes and inflammation within the TMJ. It is one of the first investigations requested. A common finding is an inflammed and disrupted articular disc. In the image below, there is bony changes as well as a displaced disc.
An MRI slice of a patient with a painful clicky jaw joint
Computer Tomography Imaging(CT scanning)
For more definitive imaging of the bony anatomy, CT imaging is the gold standard. This can assess the degree of bone destruction and also is required for planning in total joint replacement.
This is a CT image of a patient with end stage TMJ degenerative disease after trauma. The jaw joints were fractured in an accident many years earlier and has led to the irregular images seen.
Certain blood tests are used to help rule out or diagnose conditions such as Rheumatoid Arthritis. Often inflammatory conditions are assocaited with TMJ dysfunction and these screening tools can aid diagnosis. Various antibody tests will be requested depending upon the clinical situation.
Various nerve blocks in the facial region are useful for ruling in or out an intra- or extra-articular problem. These can also elicit if central sensitisation may be present. Some diagnostic nerve blocks that are commonly used in our practice are:
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